Automatic stop device for sewing machines



y 1946. w. A. BEHRENS 2,400,529

AUTOMATIC STOP DEVICE FOR SEWING MACHINES Filed 001;. 28, 1944 2Sheets-Sheet 1 IN VEN TOR.

Walk/*1 Brirrnrs I May 1945- w. A. BEHRENS 2,400,529 7 AUTOMATIC STOPDEVICE FOR SEWING MACHINES I Filed Oct. 28, 1944 2 Sheets-Sheet 2Waiferfl. Be/rrms Patented M 6 f UNITED STATES PATENT OFFICE Walter A.Behrens, Jamaica, N. 2., nssignor m Pnthe Tool Manufacturing Co. Inc.,Long Island City, N. Y., a corporation of New York Application October28, 1944, Serial No. 560,861

7 Claims. (Cl. 1l2219) use with sewing machines employing a consider-'able number of needles in'which the automatic stopping of the motor,upon failure of any one of the numerous threads, is of specialimportance due to the difliculty of immediately detecting such afailure. I

The present, invention permits to overcome the shortcomings of thedevices of the prior art and is specifically directed to the provisionof novel means controlled by the tensioning of the threads in apredetermined phase of the stitching cycle and operative to stop themotor of the sewing machine whenever any one of the threads fails to betensioned due to the breaking thereof or other causes. One object of theinvention is to provide means of the aforementioned character adapted tobe most advantageously employed in multineedle sewing machines andembodying thread.

controlled contact units that are simpl and inexpensive to manufactureand small and compact in construction, so as to be easily arranged toform rows of closely spaced units adapted for association with a numberof needle threads fed through the machine in close proximity to eachother.

Another object of the invention is to provide a thread-controlledautomatic stop device, as aforementioned, comprising contact unitsdependable in operation, which are concealed within a supportingstructure and are protected against dust so as to substantiallyeliminate an possibility of failure of the device.

Since in multi-needle sewing machines, use of all the needles is' notalways required, it is a further object of the invention to providethreadcontrolled contact units of the character described that may beselectively and rapidly rendered inoperative, by merely rotating thesame through a fixed angle to an position.

These and other objects will become apparent in the followingdescription of the invention illustrated in the drawings, wherein:

Fig. 1 is an end elevational view or associated elements, including abottom bar assembly," of

a, sewing machine embodying an automatic stop ions-elements forming thebottom bar assembly.

Fig. 3 is an enlarged front'elevational view of a portion of the bottombar assembly comprising a pair of contact units according to theinvention, one oi which has been rendered inoperative.

Fig. '4 is a vertical section on line fl-d of Fig. 3, in the directionof the arrows, illustrating the position of an operative contact unit"when the thread associated therewith is tensioned.

Fig. 5 isa similar vertical section illustrating the position of thecontact unit when its thread is not tensioned.

Fig. 6 is a vertical section, on line d6 of Fig. 3, through aninoperative contact unit.

Fig. '1 is a diagrammatical illustration of the ported stationary bar II, an insulating member or block l2, a. contact element or strip l3 andaplurality of contact units. through which the threads pass. Saidstructure is located underneath an oscillating take-up" bar It and afixed bar I] provided with the usual tension devices l8 for insuringuniform feed of the threads, and will fixed bar I1, is then leddownwardly and through one of the contact units H of the bottom barassembly, thence upwardly to one of eyelets 2| of the take-up bar Ii andfinally downwardly again to a sewing needle 22. As will be apparent, theoscillating take-up bar IE will therefore, once .during the stitchingcycle, tension all the threads in use in the machine and cause thethreads to exert an upward pull on the respective contact units llthrough which they pass, for the purpose and with the results to belater described.

With the exception of the bottom bar assembly II, which will behereafter described more in detail, the aforementioned elements areconventional and only so much of the structure thereof has been shown inthe drawings as is required to illustrate the relation thereto of thebottom bar assembly I and to permit a complete understanding of theinvention. The stationary bar II is grooved to provide therein aplurality of recesses 23 uniformly spaced cally and rotatably movabletherein. Each of the contact units consists of a body formed of aporcelain eyelet 2G and-a pair ofbrass eyelets or grommets 21, 28,assembled on the porcelain eyelet and having flanges that extend injuxtapositake-up bar I6 is operated to tension the threads I I. At thatmoment, therefore, all the contactunits I4 are displaced upwardly to-theposition of Fig. 4, and consequently no current will flow to the relay45 notwithstanding the closing of the switch 44, so that the operationof th motorwill tion to opposed faces of the bar II to prevent tionedinsulating block I2, of Bakelite" or like material, which is offsetrelative to the bar to. provide a projecting portion orled'ge underneaththe flanges of the grommets 23. The contact strip not be interrupted.

Should, however, any of the threads be broken,

or for any other reason not under tension at the instantof the take-up,the respective contact unit I4 will retain its strip-contacting positionunder the influence of its spring'25, and will bridge the.

circuit thereby permitting ,flow'of current to the relay 45 andcausingthe solenoid 43 to be energized to open the motor circuit switches 42and immediately shut off the motor.

- Since in a multi-needle sewing machine certain of the needles maysometimes not be in use, and

or element I3, preferably made of brass, is secured to the block I2, asby means -of screws 34, opposite the projecting portion of the block,and is provided with spaced projections or bosses 36 alined with thecontact units I4, inwardly of the flanges of -the.grommets 21.

The contact units I4 are normally disposed in I maintain the grommet 21thereof in surface en-' gagement with the respective boss 38 of thecon.- tact strip I3 alined therewith, as shown in Fig. 4, provided thethread I9 passing through the porcelain eyelet 26 of the unitis slack.Upon tensioningof the thread, following the operation of the take-up baronce during each stitching cycle, as aforementioned, the unit I4 will bepulled upwardly away from the associated boss 36 of the contact stripI3, to the position illustrated in Fig. 4. Failure of any one of thethreads to displace the respective unit I4 at the instant of the takeup,will result in stopping the motor which drives the machine, in themanner that will now be-de; scribed. 1

As illustrated in Fig. 7, the power circuit of the electric motor of thesewing machine comprises normally clos d switches 42, which may be thecontact units associated therewith would then not be controlled by thethreads, it is apparent from the foregoing that such contact units mustbe rendered inoperative to prevent the same from stopping the machine insynchronism with the operation of the take-up bar.

For this purpose, it is suflicient to rotate an desired contact unitsthrough an angle of 90 degrees,-to dispose the edge 3| of the flange ofthe grommet 28 thereof parallel to the upper face of the projectingportion of the insulating block I2. In such a position of the flange,the unit is prevented from moving into contact with the respective bossof the contact strip I3 by the abutment of the edge 3! 'on theinsulating block I2, as shown in Fig. 6, and is therefore ineffective tobridge the circuit described at any time. Manifestly, the unit mayreadily be returned to its operative position through aninversedirectional movement thereof. I i

It 'is to be understood that numerous changes and modifications may bemade in the structure described and illustrated in the drawings withoutdeparting from the spirit of the invention or exceeding thescope of theclaims;

I claim: 1 In a motor driven multi-needle sewing machine having meansfor' tensioning the threads in a predetermined phase of'eachstitchingcycle,

opened to shut off ,he'motor by a solenoid 43. Q

' This latter forms part of an open electric circuit,

suitablyconnected to the motor power circuit,

4 which also includes a switch and a vacuum tube relay 45 for energizingthe solenoid 43, and 3 which is bridged by the contact strip l3 andcon.- tact-units I4 when these latter are in the stripcontactingposition-shown in Fig. 5. Normally,

during operation of the machine, the threads are A shaft 46 driven fromthe motor 4|! through suitable speed-reducing transmission, carries acam 41 acting to close the switch 44 once during each stitching cycle atthe instant in which the a normaly open electric circuit, means actuatedupon closing'of said circuit for stopping the motor, and means forcontrolling the closing of said circuit, said last mentioned meanscomprising a normally open switch periodically closed in synchronismwith the tensioning of the threads and a plurality of contact units eachassociated with bridging position simultaneously with the closing havingmeans for tensioning the threads in a,

predetermined phase of each stitching cycle, a normally open electriccircuit, a contact element connected in said circuit, a plurality ofcontact units each associated with one of the threads,

said units being normally held in contact with said contact element tobridge said .circuit and being displaceable by the tensioning of thethreads from said normal position thereof, means effective upon closingof the circuit to stop the motor. means for closing the circuit insynchronism with the tensioning of the threads, the tensioning of thethreads simultaneously causing the contact units to be displaced by thethreads fromsaid normal position thereof thereby normally preventing theactuation of the means for stopping the motor, the failure of any ne ofthe threads to be tensioned causing the respective contact unit tomaintain its normal circuit bridging position thereby permittingoperation of the means for stopping the motor.

3. In a motor driven multi-needle sewing machine having means fortensionlng the threads in a predetermined phase of each stitching cycle,a stationary bar, an insulating block and a contact element carried bysaid bar, a plurality of contact units movably mounted in said bar, eachcomprising a body through which one of the threads passes and a pair ofmetal eyelets mounted on said body one of which is maintained in contactwith said contact element in the normal position of the unit, said unitsbeing displaceable by the tensioning of the threads from said normalposition thereof, means effective at'the instant of the tensioning ofthe threads to stop the motor whenever any one of said contact unitsmain- I tains its normal position due to the failure of the respectivethread to displace the same, each of said units being rotatable in saidstationary bar and one of said metal eyelets of the unit having a flangeadaptcd'to engage in the rotation of the unit said aforementionedinsulating block to lock the unit in a position wherein theaforementioned contact eyelet is prevented from contacting said contactelement, whereby any one of the units may be selectively renderedinoperative.

i. In a motor driven multi-needle sewing machine comprising means fortensioning the threads in a predetermined phase of each stitching cycle,a normally open electric circuit including a switch periodically closedin synchronism with the tensioning of the threads and means for stoppingthe motor upon closing of said cir cult, a device for controlling theclosing of said circuit comprising a stationary supporting memher, afixed contact element associated with said member and connected in thecircuit, a plurality of contact units movably mounted in the supportingmember, and means'for normally maintainin said units in contact withsaid fixed contact element to bridge the circuit, each of said unitsbeing associated with one of the threads and adapted to be displaced bythe tensioning of the respective thread from its normal position, thefailure of any one of the threads to be tensioned causing the associatedcontact unit to maintain its normal position thereby determining theclosing of the circuit.

5. In a motor driven multi-needle sewing machine comprising means fortensioning the.

threads in a predetermined phase of each stitching cycle, a normallyopen electric circuit including a switch periodically closed insynchronism with the tensioning of the threads and means for stoppingthe motor uponclosing of said circuit, a device for controlling theclosing of said I circuit comprising a stationary supporting member,aflxed contact element associated with said member and connected in thecircuit, a plurality of contact units movably mounted in the supportingmember, and means for normally maintaining said units in contact withsaid fixed contact element to bridge the circuit, each of said unitsbeing associated with one of the threads and adapted to be displaced bythe tensioning of the respective thread'from its normal position, thefailure of any one of the threads to be tensioned causing the associatedcontact unit to maintain its normal position thereby determinin theclosing of the circuit, said contact units being rotatable in thesupporting member to a position in which contact thereof with the fixedcontact element is prevented 'at all times whereby any one of the unitsmay be rendered selectively inoperative. I

6. In a motor driven multi-needle sewing machine comprising means fortensioning the threads in a predetermined phase of each stitching cycle,a normally open electric circuit includfor normally maintaining saidunits in circuitbridging position, each of said units being displaceableby thetensioning of the respective thread from its normal position andthe failure or any one of the threads to be tensioned causing theassociated contact unit to maintain its normal position therebydetermining the closing of the circuit,

7. In a motor driven multi-needie sewing machine comprising take-upmeans for tensioning the threads in a predetermined phase of eachstitching cycle, a normally open electric circuit including aswitch'periodically closed in synchronism with the tensioning oi thethreads and means for stopping the motor upon closing of said circuit, adevice for controlling the closing of said circuit comprising astationary support, an insulating block and a contact element connectedin said circuit carried by said support, a plurality of contact unitsmovably mounted in said support, each comprising a body through whichone of the threads passes and a member carried by said body adapted tocontact said contact element to bridge the circuit, and resilient meansmounted in the support for normally maintaining said units incircuit-bridging position, each of the units being displaceable bythetensioning of the respective thread from its normal position and thefailure of any one of the threads to be tensioned causing the associatedcontact unit to maintain its normal position thereby determining theclosing of the circuit, each unit being rotatable in the support to aposition in which contact of the member carried by the body of the unitwith the contact element aforementioned is prevented at all times,whereby any one of the units may be rendered selectively inoperative. vI WALTER A. BEHRENS.

